Solution composition for forming oxide thin film and electronic device including the oxide thin film

ABSTRACT

A solution composition for forming an oxide thin film may include a first compound including zinc, a second compound including indium, and a third compound including magnesium or hafnium, and an electronic device may include an oxide semiconductor including zinc, indium, and magnesium. The zinc and hafnium may be included at an atomic ratio of about 1:0.01 to about 1:1.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under U.S.C. §119 to Korean PatentApplication No. 10-2009-0031000 and No. 10-2010-0026314 filed in theKorean Intellectual Property Office (KIPO) on Apr. 9, 2009 and Mar. 24,2010, respectively, the entire contents of which are incorporated hereinby reference.

BACKGROUND

1. Field

Example embodiments relate to a solution composition for forming anoxide thin film and an electronic device including the oxide thin film.

2. Description of the Related Art

Electronic devices, e.g., resistors, capacitors, diodes, and thin filmtransistors, are used in various fields. Thin film transistors (TFT) areused for a switching and driving device in a flat panel display, e.g., aliquid crystal display (LCD), an organic light emitting diode display(OLED display), and an electrophoretic display (EPD).

The semiconductor is one of the primary components for determining thecharacteristics of such electronic devices. Such a semiconductor isgenerally composed of silicon (Si). Silicon is classified into amorphoussilicon and polycrystalline silicon depending upon the crystal shape.Amorphous silicon may be obtained by a relatively simple manufacturingprocess, but has insufficient charge mobility to provide highperformance devices, while polycrystalline silicon has increased chargemobility, but requires a step of crystallizing silicon which increasesthe cost and complicates the process.

In order to compensate for shortcomings of amorphous silicon andpolycrystalline silicon, oxide semiconductors may be used. However theoxide semiconductors may deteriorate stability and reliability ofelectronic devices because controlling their electric characteristicsmay be difficult.

SUMMARY

Example embodiments provide a solution composition for forming an oxidethin film being capable of improving electrical characteristics ofelectronic devices. Example embodiments also provide an electronicdevice including the oxide thin film.

According to example embodiments, a solution composition for forming anoxide thin film may include a first compound including zinc, a secondcompound including indium, and a third compound including magnesium.

The zinc and magnesium may be included at an atomic ratio of about1:0.01 to about 1:4. The zinc and indium may be included at an atomicratio of about 1:10 to about 10:1. The zinc and indium may be includedat an atomic ratio of about 1:5 to about 5:1.

The zinc and indium may be included at an atomic ratio of about 1:10 toabout 1:1. The zinc and indium may be included at an atomic ratio ofabout 1:5 to about 1:1. The third compound may include at least one ofmagnesium acetate, magnesium alkoxide, magnesium halide, magnesiumnitrate, magnesium sulfate, magnesium carbohylate, magnesium carbonate,and hydrates thereof.

The first compound may include at least one of zinc hydroxide, zincalkoxide, zinc citrate, zinc acetate, zinc carbonylate, zinc carbonate,zinc (meth)acrylate, zinc nitrate, zinc acetylacetonate, zinc halide,zinc thiocarbamate, zinc sulfonate, zinc undecylate, zinc phosphate,zinc borate, and hydrates thereof. The second compound may include atleast one of indium hydroxide, indium alkoxide, indium citrate, indiumacetate, indium carbonate, indium (meth)acrylate, indium nitrate, indiumacetylacetonate, indium halide, indium thiocarbamate, indium sulfonate,indium undecylate, indium borate, and hydrates thereof.

The first compound may include zinc acetate hydrate and the secondcompound may include indium nitrate hydrate. The solution compositionmay further include at least one of an alcohol amine compound, an alkylammonium hydroxy compound, an alkyl amine compound, ketone compound, anacid compound, a base compound, and deionized water.

According to example embodiments, an electronic device may include anoxide semiconductor including zinc, indium, and magnesium. The oxidesemiconductor may include the zinc and magnesium at an atomic ratio ofabout 1:0.01 to about 1:4. The zinc and indium may be included at anatomic ratio of about 1:10 to about 10:1. The zinc and indium may beincluded at an atomic ratio of about 1:5 to about 5:1.

The zinc and indium may be included at an atomic ratio of about 1:10 toabout 1:1. The zinc and indium may be included at an atomic ratio ofabout 1:5 to about 1:1. The electronic device may be a thin filmtransistor that further includes the oxide semiconductor on a gateelectrode, a source electrode electrically connected to the oxidesemiconductor, and a drain electrode electrically connected to the oxidesemiconductor and facing the source electrode.

A solution composition for forming an oxide thin film according toexample embodiments may include a first compound including zinc, asecond compound including indium, and a third compound includinghafnium. The zinc and hafnium may be included at an atomic ratio ofabout 1:0.05 to about 1:0.3.

The first compound may include zinc acetate hydrate, the second compoundmay include indium nitrate hydrate, and the third compound may includehafnium chloride. The solution composition may further include at leastone of an alcohol amine compound, an alkyl ammonium hydroxy compound, analkyl amine compound, ketone compound, an acid compound, a basecompound, and deionized water.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings. FIGS. 1-10 represent non-limiting, example embodiments asdescribed herein.

FIG. 1 is a graph showing the current characteristics of the thin filmtransistors according to Examples I-1 to I-4 and Comparative Example 1,

FIGS. 2A and 2B are graphs showing hysteresis characteristics of thethin film transistors according to Examples I-1 to I-4,

FIG. 3 is a graph showing the current characteristics of the thin filmtransistors according to Examples II-1 to II-3 and Comparative Example,

FIG. 4 is a graph showing hysteresis characteristics of the thin filmtransistors according to Examples III-1 to III-3,

FIG. 5 is a graph showing current characteristics of thin filmtransistors according to Examples IV-1 to IV-4 and Comparative Example2,

FIGS. 6A and 6B are graphs showing hysteresis characteristics of thethin film transistors according to Example IV-2, Example IV-3 andComparative Example 2, and

FIG. 7 is a cross sectional view of a thin film transistor according toexample embodiments, and

FIGS. 8 to 10 are cross-sectional views sequentially showing a method ofmanufacturing a thin film transistor shown in FIG. 7.

DETAILED DESCRIPTION

Example embodiments will be described more fully hereinafter withreference to the accompanying drawings. Example embodiments may,however, be embodied in many different forms and should not be construedas limited to example embodiments set forth herein. Accordingly, exampleembodiments are merely described below, by referring to the figures, toexplain aspects of the present description. In the drawings, the sizesor thicknesses of elements are exaggerated for clarity, and likereference numerals denote like elements. It should be noted that theseFigures are intended to illustrate the general characteristics ofmethods, structure and/or materials utilized in certain exampleembodiments and to supplement the written description provided below.These drawings are not, however, to scale and may not precisely reflectthe precise structural or performance characteristics of any givenexample embodiment, and should not be interpreted as defining orlimiting the range of values or properties encompassed by exampleembodiments. For example, the relative thicknesses and positioning ofmolecules, layers, regions and/or structural elements may be reduced orexaggerated for clarity. The use of similar or identical referencenumbers in the various drawings is intended to indicate the presence ofa similar or identical element or feature. As used herein, the terms “a”and “an” are open terms that may be used in conjunction with singularitems or with plural items.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Like numbers indicate like elementsthroughout. As used herein the term “and/or” includes any and allcombinations of one or more of the associated listed items.

It will be understood that, although the terms “first”, “second”, etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another element, component, region, layer or section. Thus,a first element, component, region, layer or section discussed belowcould be termed a second element, component, region, layer or sectionwithout departing from the teachings of example embodiments.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises”, “comprising”, “includes” and/or “including,” if usedherein, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Example embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized embodiments (and intermediate structures) of exampleembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, example embodiments should not be construed aslimited to the particular shapes of regions illustrated herein but areto include deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to limit the scope ofexample embodiments.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments belong. Itwill be further understood that terms, such as those defined incommonly-used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand will not be interpreted in an idealized or overly formal senseunless expressly so defined herein.

Hereinafter, a solution composition according to example embodiments isdescribed. The solution composition according to example embodiments maybe a precursor solution used for forming an oxide semiconductor thinfilm.

The precursor solution according to example embodiments may include acompound containing zinc (Zn) (hereinafter referred to as“zinc-containing compound”), a compound containing indium (In)(hereinafter referred to as “indium-containing compound”), and acompound containing magnesium (Mg) (hereinafter, referred to as‘magnesium-containing compound”).

The zinc-containing compound may be at least one of a zinc salt and ahydrate thereof, but is not limited thereto. Examples of thezinc-containing compound may include at least one of zinc hydroxide;zinc alkoxide; zinc citrate; zinc acetate, e.g., zinc trifluoroacetate;zinc carbonylate; zinc carbonate; zinc (meth)acrylate; zinc nitrate;zinc acetylacetonate, e.g., zinc hexafluoroacetylacetonate; zinc halide,e.g., zinc fluoride, zinc chloride and/or zinc perchlorate; zincthiocarbamate, e.g., zinc dimethyldithiocarbamate and/or zincdiethyldithiocarbamate; zinc sulfonate, e.g., zinctrifluoromethanesulfonate; zinc undecylate; zinc phosphate; zinc borate,e.g., zinc tetrafluoroborate; and hydrates thereof.

The indium-containing compound may include an indium salt, and itshydrate, but is not limited thereto. Examples of the indium-containingcompound may include at least one of indium hydroxide; indium alkoxide;indium citrate; indium acetate; indium carbonate; indium (meth)acrylate;indium nitrate; indium acetylacetonate; indium halide, e.g., indiumchloride and/or indium fluoride; indium thiocarbamate; indium sulfonate;indium undecylate; indium borate; and hydrates thereof.

The magnesium-containing compound may include a magnesium salt, and itshydrate, but is not limited thereto. Examples of themagnesium-containing compound may include at least one of magnesiumhalides, e.g., magnesium chloride and/or magnesium fluoride; magnesiumacetate; magnesium carbonate; magnesium alkoxide; magnesium nitrate;magnesium sulfate; magnesium carbonylate; and hydrates thereof.

Combining the zinc-containing compound, indium-containing compound, andmagnesium-containing compound in various ways may be possible. Inexample embodiments, when the zinc-containing compound is zinc acetatehydrate, the indium-containing compound may be indium nitrate hydrate,and the magnesium-containing compound may be magnesium nitrate hydrate.Therefore, providing a solution composition with increased solubilityand ensuring a relatively uniform thin film may be possible.

The atomic ratio of zinc and indium may range from about 1:10 to about10:1 in the precursor solution. In the range, the atomic ratio of zincand indium may range from about 1:10 to about 1:1, about 1:5 to about5:1, or about 1:5 to 1:1. The atomic ratio is maintained after formingthe oxide semiconductor thin film. When zinc and indium are included inthe range, the oxide thin film obtained from the precursor solution mayexhibit the semiconducting characteristics.

The atomic ratio of zinc and magnesium may range from about 1:0.01 toabout 1:4 in the precursor solution. In addition, an atomic ratio of thesum of indium and zinc to magnesium ranges from about 1:0.004 to about1:0.4 in the precursor solution. The atomic ratio is maintained afterforming the oxide semiconductor thin film. The magnesium may act as afactor for controlling threshold voltage and current characteristics ofelectronic devices when an oxide semiconductor obtained from theprecursor solution is applied to an electronic device, e.g., a thin filmtransistor. When the magnesium is included in the range, an improvedthreshold voltage and current characteristics may be obtained andsufficient on-current may be obtained because the amount of indium andzinc in the oxide semiconductor is not significantly decreased.

The zinc-containing compound, indium-containing compound, andmagnesium-containing compound may respectively be included at about 0.01to about 30 wt % based on the total amount of precursor solution. Wheneach component is included in the range, obtaining solubility may bepossible.

The precursor solution may further include a solution stabilizer. Thesolution stabilizer may include at least one selected from the groupconsisting of an alcohol amine compound, e.g., monoethanol amine,diethanol amine, triethanol amine, N,N-methylethanol amine, aminoethylethanol amine, N-t-butylethanol amine, N-t-butyldiethanol amine, anddiethylene glycol amine; an alkyl ammonium hydroxy compound, e.g.,tetramethylammonium hydroxide; an alkyl amine compound, e.g.,methylamine, ethylamine, and monoisopropyl amine; a ketone compound,e.g., acetylacetone; an acid compound, e.g., hydrochloric acid, nitricacid, sulfuric acid, and acetic acid; a base compound, e.g., ammoniumhydroxide, potassium hydroxide, and sodium hydroxide; alkoxy alcohol,e.g., 2-(aminoethoxy)ethanol; and deionized water.

The solution stabilizer may be included in a precursor solution toincrease the solubility of other components. The oxide semiconductorthin film from the precursor solution may be formed uniformly. Theamount of solution stabilizer may be varied depending upon the type andamount of other components, but the solution stabilizer may be includedat about 0.01 to about 30 wt % based on the total amount of theprecursor solution. When the solution stabilizer is included in therange, the solution stabilizer may improve the solubility and thin filmcoating properties.

The zinc-containing compound, the indium-containing compound, themagnesium-containing compound, and the solution stabilizer may be mixedin a solvent to provide a precursor solution. The zinc-containingcompound and the indium-containing compound may be respectively preparedby providing a solution that is mixed in each solvent, mixing the same,and mixing them with a magnesium-containing compound or a solutionincluding a metal-containing compound. A solution stabilizer may beadded to each solution of components or may be added after mixing eachsolution. Alternatively, a precursor solution may be prepared by mixinga zinc-containing compound, an indium-containing compound, amagnesium-containing compound, and a solution stabilizer in a solvent.

The solvent may be any solvent that dissolves the above components, andis not particularly limited. Non-limiting examples of the solvent mayinclude at least one selected from deionized water, methanol, ethanol,propanol, isopropanol, 2-methoxyethanol, 2-ethoxyethanol,2-propoxyethanol 2-butoxyethanol, methylcellosolve, ethylcellosolve,diethyleneglycol methylether, diethyleneglycol ethylether,dipropyleneglycol methylether, toluene, xylene, hexane, heptane, octane,ethylacetate, butylacetate, diethyleneglycol dimethylether,diethyleneglycol dimethylethylether, methylmethoxy propionic acid,ethylethoxy propionic acid, ethyl lactic acid, propylene glycolmethylether acetate, propylene glycol methylether, propylene glycolpropylether, methyl cellosolve acetate, ethyl cellosolve acetate,diethylene glycol methylacetate, diethylene glycol ethylacetate,acetone, methyl isobutyl ketone, cyclohexanone, dimethyl formamide(DMF), N,N-dimethyl acetamide (DMAc), N-methyl-2-pyrrolidone,γ-butyrolactone, diethylether, ethylene glycol dimethylether, diglyme,tetrahydrofuran, acetylacetone, and acetonitrile.

The solvent may be included as the balance amount based on the totalamount of the solution composition excepting the amount of thecomponents. The zinc-containing compound, indium-containing compound,and magnesium-containing compound may be precursors of an oxidesemiconductor thin film, and grow to a magnesium indium zinc oxide(MgIZO) thin film including indium, zinc, and magnesium through heattreatment as follows.

As described above, the oxide semiconductor may be formed as a solution,and therefore, simplifying the process may be possible without acomplicated high-cost manufacturing process, e.g., vacuum deposition.

The precursor solution according to example embodiments may include azinc-containing compound, an indium-containing compound, and a compoundincluding hafnium (Hf) (hereinafter, referred to as “hafnium-containingcompound”).

The zinc-containing compound and indium-containing compound may be thesame as above described, and the atomic ratio of zinc and indium mayrange from about 1:10 to about 10:1 in the precursor solution.

The hafnium-containing compound may be at least one of a hafnium saltand a hydrate thereof, but is not limited thereto. Examples of thehafnium-containing compound may include at least one of hafnium halide,e.g., hafnium chloride and/or hafnium fluoride; hafnium acetate; hafniumcarbonyl; hafnium carbonate; hafnium nitrate; hafnium alkoxide; andhydrates thereof.

In example embodiments, the atomic ratio of zinc and hafnium may rangefrom about 1:0.01 to about 1:1 in the precursor solution, and in exampleembodiments, the atomic ratio of zinc and hafnium may range from about1:0.05 to about 1:0.3. The hafnium may act as a factor for controllingthe threshold voltage and current characteristics when the oxidesemiconductor obtained from the precursor solution is applied to anelectronic device, e.g., a thin film transistor. When hafnium isincluded in the range, the threshold voltage and current characteristicsmay be obtained, and simultaneously, a sufficient on-current may beobtained because the amount of zinc and indium is not significantlydecreased.

The zinc-containing compound, indium-containing compound, andhafnium-containing compound may respectively be included at about 0.01to about 30 wt % based on the total amount of precursor solution. Wheneach component is included in the range, obtaining solubility may bepossible.

The precursor solution may further include a solution stabilizer. Thezinc-containing compound, indium-containing compound, andhafnium-containing compound may be precursors of an oxide semiconductorthin film, and grow to a hafnium indium zinc oxide (HfIZO) thin filmincluding indium, zinc, and hafnium through heat treatment as follows.

As described above, the oxide semiconductor may be formed as a solution,so simplifying the process may be possible without complicated high-costmanufacturing process, e.g., vacuum deposition.

The magnesium indium zinc oxide (MgIZO) or hafnium indium zinc oxide(HfIZO) may be applied as a semiconductor of an electronic device, e.g.,a thin film transistor. Hereinafter, a thin film transistor that themagnesium indium zinc oxide (MgIZO) or hafnium indium zinc oxide (HfIZO)is applied to is described referring to the drawings.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. Like reference numerals designate likeelements throughout the specification. It will be understood that whenan element such as a layer, film, region, or substrate is referred to asbeing “on” another element, it can be directly on the other element orintervening elements may also be present. In contrast, when an elementis referred to as being “directly on” another element, there are nointervening elements present.

FIG. 7 is a cross-sectional view showing a thin film transistoraccording to example embodiments. Referring to FIG. 7, the thin filmtransistor may include a gate electrode 124 formed on a substrate 110,and a gate insulating layer 140 formed to cover the whole surface of thesubstrate and the gate electrode 124.

An oxide semiconductor 154 may be formed to overlap the gate electrode124 on the gate insulating layer 140. The oxide semiconductor 154 may bemade of magnesium indium zinc oxide (MgIZO) including indium (In), zinc(Zn), and magnesium (Mg) or hafnium indium zinc oxide (HfIZO) includingindium (In), zinc (Zn), and hafnium (Hf).

A carrier concentration of the oxide semiconductor 154 may be controlledby a number of the oxygen vacancy. Magnesium (Mg) and hafnium (Hf) hasoxidation power at ion state to decrease oxygen vacancy, and thereby,carrier concentration may be more easily controlled. In addition, whenmagnesium (Mg) and hafnium (Hf) are oxidized, their band gaps may belarger and conductivity may be decreased to reduce leakage current.Therefore, when magnesium indium zinc oxide (MgIZO) or hafnium indiumzinc oxide (HfIZO) is applied to an electronic device, e.g., a thin filmtransistor, threshold voltage and current characteristics may beimproved.

A source electrode 173 and a drain electrode 175 may be formed to faceeach other on the oxide semiconductor 154, and may be electricallyconnected with the oxide semiconductor 154 when a predetermined or givenvoltage is applied. A channel Q of the thin film transistor may beformed in the oxide semiconductor 154 between the source electrode 173and the drain electrode 175.

Hereinafter, a method of manufacturing a thin film transistor as shownin FIG. 5 is described referring to FIGS. 8 to 10. FIGS. 8 to 10 arecross-sectional views sequentially showing a method of manufacturing athin film transistor shown in FIG. 7.

The zinc-containing compound, indium-containing compound,magnesium-containing compound, and solution stabilizer may be mixed in asolvent to obtain a magnesium indium zinc oxide (MgIZO) precursorsolution, or the zinc-containing compound, indium-containing compound,hafnium-containing compound, and solution stabilizer may be mixed in asolvent to obtain a hafnium indium zinc oxide (HfIZO) precursorsolution. Each component may be mixed in a solvent by agitatingprecursor solution, at for example, room temperature (about 25° C.) toabout 100° C. for about 1 to about 100 hours using an agitator orultrasonic waves. The agitating improves dissolubility and thin filmcoating properties. Aging may further be performed about 1 to about 240hours. The obtained precursor solution may be present in a sol state,e.g., a colloidal suspension of solid particles in a liquid.

As illustrated in FIG. 8, a conductive layer (not shown) is deposited onthe substrate 110, e.g., glass, silicon, or plastic, and subjected tophotolithography to provide the gate electrode 124.

As shown in FIG. 9, an insulating layer, e.g., silicon oxide (SiO₂)and/or silicon nitride (SiN_(x)), and an organic insulator may bedeposited on the gate electrode 124 to provide the gate insulating layer140.

As shown in FIG. 10, the oxide semiconductor 154 may be formed on thegate insulating layer 140. The oxide semiconductor 154 may be formedusing a method of spin coating, slit coating, Inkjet printing, spraying,dipping, roll-to-roll or nano imprinting the magnesium indium zinc oxide(MgIZO) precursor solution including indium-containing compound,zinc-containing compound and magnesium-containing compound, or hafniumindium zinc oxide (HfIZO) precursor solution including indium-containingcompound, zinc-containing compound and hafnium-containing compound.

The precursor solution may be subjected to heat treatment to grow amagnesium indium zinc oxide (MgIZO) thin film or a hafnium indium zincoxide (HfIZO) thin film. Prebaking at a relatively low temperature totransform a sol solution to a gel may be performed before heat treatmentat a relatively high temperature.

As shown in FIG. 7, a conductive layer (not shown) may be deposited onthe oxide semiconductor 154 and subjected to photolithography to providethe source electrode 173 and the drain electrode 175.

The following examples illustrate example embodiments in more detail.However, it is understood that the scope of example embodiments is notlimited to these examples.

Example I-1 Preparation of Precursor Solution

Zinc acetate dihydrate, indium nitrate hydrate, and magnesium nitratehydrate are prepared. The zinc acetate dihydrate, indium nitratehydrate, magnesium nitrate hydrate, and a solution stabilizer are addedto a solvent and mixed to form a mixed solution of about 0.5M. Thesolvent is 2-methoxyethanol and is used in an amount of about 25 to 28ml depending on an amount of the magnesium. The solution stabilizer ismonoethanol amine and acetic acid at a weight ratio of about 1:1 at each4 g in the solvent.

The mole ratio (atomic ratio) of the indium and zinc is fixed at about3:2 and the atomic ratio of the zinc and magnesium is fixed at about1:0.1. Subsequently, the resultant is agitated at about 70° C. for about1 hour on a hot plate and aging is performed for 24 hours to obtain amagnesium indium zinc oxide precursor solution in a sol state.

Fabrication of the Thin Film Transistor

On the glass substrate, molybdenum tungsten (MoW) is deposited at anabout 2,000 Å thickness and a predetermined or given shaped gateelectrode is formed using photolithography. Silicon nitride is depositedusing a chemical vapor deposition (CVD) method at an about 2000 Å toprovide a gate insulating layer. The precursor solution according toexample embodiments is spin-coated on the gate insulating layer andprebaked. The spin coating is performed at about 3000 rpm for about 30seconds and prebaking is performed at about 300° C. for about 5 minuteson a hot plate. A substrate is placed in a furnace and heat-treated atabout 550° C. for about 2 hours to grow a magnesium indium zinc oxide(MgIZO) semiconductor thin film. Tantalum is deposited at an about 1000Å thickness, and a source electrode and a drain electrode are formedusing a shadow mask.

Example I-2

The precursor solution and the thin film transistor are preparedaccording to the same method as in Example I-1, except that the atomicratio of the zinc and magnesium is about 1:0.2.

Example I-3

The precursor solution and the thin film transistor are preparedaccording to the same method as in Example I-1, except that the atomicratio of the zinc and magnesium is about 1:0.3.

Example I-4

The precursor solution and the thin film transistor are preparedaccording to the same method as in Example I-1, except that the atomicratio of the zinc and magnesium is about 1:0.4.

Example II-1 Preparation of Precursor Solution

Zinc acetate dihydrate, indium nitrate hydrate, and magnesium nitratehydrate are prepared. The zinc acetate dihydrate, indium nitratehydrate, magnesium nitrate hydrate, and a solution stabilizer are addedto a solvent and mixed to form a mixed solution of about 0.2M. Thesolvent is 2-methoxyethanol and the solution stabilizer is monoethanolamine and acetic acid.

The mole ratio (atomic ratio) of the indium and zinc is fixed at about3:1 and the atomic ratio of the zinc and magnesium is fixed at about1:0.1. Subsequently, the resultant is agitated at about 70° C. for about1 hour on a hot plate and aging is performed for about 24 hours toobtain magnesium indium zinc oxide precursor solution in a sol state.

Fabrication of Thin Film Transistor

On the glass substrate, molybdenum (Mo) are deposited at an about 2000 Åthickness to form gate electrode. Silicon nitride is deposited using achemical vapor deposition (CVD) method at an about 4000 Å to provide agate insulating layer. The precursor solution according to the presentexample is spin-coated on the gate insulating layer and prebaked. Thespin coating is performed at about 1000 rpm for about 30 seconds andprebaking is performed at about 250° C. for about 1 minute on a hotplate. A substrate is placed on a hot plate and heat-treated at about450° C. for about 1 hour to grow a magnesium indium zinc oxide (MgIZO)semiconductor thin film. Aluminum is deposited at an about 1000 Åthickness, and a source electrode and a drain electrode are formed usinga shadow mask.

Example II-2

The precursor solution and the thin film transistor are preparedaccording to the same method as in Example II-1, except that the atomicratio of the zinc and magnesium is about 1:0.3.

Example II-3

The precursor solution and the thin film transistor are preparedaccording to the same method as in Example II-1, except that the atomicratio of the zinc and magnesium is about 1:0.5.

Example III-1 Preparation of Precursor Solution

Zinc acetate dihydrate, indium nitrate hydrate, and magnesium nitratehydrate are prepared. The zinc acetate dihydrate, indium nitratehydrate, magnesium nitrate hydrate, and a solution stabilizer are addedto a solvent and mixed to form a mixed solution of about 0.5M. Thesolvent is 2-methoxyethanol and the solution stabilizer is monoethanolamine and acetic acid.

The mole ratio (atomic ratio) of the indium and zinc is fixed at about9:1 and the atomic ratio of the zinc and magnesium is fixed at about1:1. Subsequently, the resultant is agitated at about 70° C. for about 1hour on a hot plate and aging is performed for about 24 hours to obtainmagnesium indium zinc oxide precursor solution in a sol state.

Fabrication of Thin Film Transistor

On the glass substrate, molybdenum (Mo) are deposited at an about 2000 Åthickness and a predetermined or given shaped gate electrode is formedusing photolithography. Silicon nitride is deposited using a chemicalvapor deposition (CVD) method at about 4000 Å to provide a gateinsulating layer. The precursor solution according to exampleembodiments is spin-coated on the gate insulating layer and prebaked.The spin coating is performed at about 3000 rpm for about 30 seconds andprebaking is performed at about 300° C. for about 5 minutes on a hotplate. A substrate is placed on a hot plate and heat-treated at about450° C. for about 3 hours to grow a magnesium indium zinc oxide (MgIZO)semiconductor thin film. Subsequently, an etch stopper layer is formedon the semiconductor thin film for protecting a channel. Molybdenum isdeposited at an about 2000 Å thickness, and a source electrode and adrain electrode are formed using a photolithography.

Example III-2

The precursor solution and the thin film transistor are preparedaccording to the same method as in Example III-1, except that the atomicratio of the zinc and magnesium is about 1:2.

Example III-3

The precursor solution and the thin film transistor are preparedaccording to the same method as in Example III-1, except that the atomicratio of the zinc and magnesium is about 1:4.

Example IV-1 Preparation of Precursor Solution

Zinc acetate dihydrate, indium nitrate hydrate, and hafnium chloride areprepared. The zinc acetate dihydrate, indium nitrate hydrate, hafniumchloride, and a solution stabilizer are added to a solvent and mixed toform a mixed solution of about 0.5M. The solvent is 2-methoxyethanol andis used in an amount of about 25 to 28 in depending on an amount of thehafnium. The solution stabilizer is monoethanol amine and acetic acid ata weight ratio of about 1:1 at each 4 g in the solvent.

The mole ratio (atomic ratio) of the indium and zinc is fixed at about3:2 and the atomic ratio of the zinc and hafnium is fixed at about1:0.05. Subsequently, the resultant is agitated at about 70° C. forabout 1 hour on a hot plate and aging is performed for about 24 hours toobtain magnesium indium zinc oxide precursor solution in a sol state.

Fabrication of Thin Film Transistor

On the glass substrate, molybdenum tungsten (MoW) are deposited at anabout 2000 Å thickness and a predetermined or given shaped gateelectrode is formed using photolithography. Silicon nitride is depositedusing a chemical vapor deposition (CVD) method at an about 2000 Åthickness to provide a gate insulating layer. The precursor solutionaccording to example embodiments is spin-coated on the gate insulatinglayer and prebaked. The spin coating is performed at about 3000 rpm forabout 30 seconds and prebaking is performed at about 300° C. for aboutminutes on a hot plate. A substrate is placed in a furnace andheat-treated at about 550° C. for about 2 hours to grow a hafnium indiumzinc oxide (MgIZO) semiconductor thin film. Tantalum is deposited at anabout 1000 Å thickness, and a source electrode and a drain electrode areformed using a shadow mask.

Example IV-2

The precursor solution and the thin film transistor are preparedaccording to the same method as in Example IV-1, except that the atomicratio of the zinc and hafnium is about 1:0.1.

Example IV-3

The precursor solution and the thin film transistor are preparedaccording to the same method as in Example IV-1, except that the atomicratio of the zinc and hafnium is about 1:0.2.

Example IV-4

The precursor solution and the thin film transistor are preparedaccording to the same method as in Example IV-1, except that the atomicratio of the zinc and hafnium is about 1:0.3.

Comparative Example 1

The precursor solution is prepared according to the same method as inExample I-1, except that magnesium nitrate hydrate is not used.

Comparative Example 2

The precursor solution is prepared according to the same method as inExample IV-1, except that hafnium chloride is not used.

Performance Evaluation 1

The thin film transistors fabricated using the precursor solutionaccording to Examples I-1 to I-4 and Comparative Example 1 are evaluatedwith respect to a threshold voltage, a current ratio, and chargemobility according to amounts of magnesium.

The evaluation results are shown in the following Table 1 and FIG. 1.FIG. 1 is a graph showing the current characteristics of the thin filmtransistors according to Examples I-1 to I-4 and Comparative Example 1.

TABLE 1 Threshod Current Voltage Ratio Mobility (Vth) (Ion/Ioff)(cm²/Vs) Example I-1 MgIZO[Mg/Zn = 0.1] −5.52 1.07 × 10³ 0.72 ExampleI-2 MgIZO[Mg/Zn = 0.2] 2.66 6.57 × 10⁶ 1.33 Example I-3 MgIZO[Mg/Zn =0.3] 2.37 2.25 × 10⁶ 0.79 Example I-4 MgIZO[Mg/Zn = 0.4] 4.54 1.05 × 10⁶0.53 Comparative IZO −24.05 1.41 × 10² 1.16 Example 1

Referring to Table 1 and FIG. 1, the thin film transistor according toExamples I-1 to I-4 shows a lower threshold voltage, a higher currentratio, and more stable charge mobility of 0.5 cm²/Vs or more. On thecontrary, the thin film transistor according to Comparative Example 1shows a higher threshold voltage and a lower current ratio due to higheroff current (I_(off)). Therefore, the magnesium indium zinc oxide(MgIZO) semiconductor thin film improves properties of the thin filmtransistor.

Performance Evaluation 2

The thin film transistors fabricated using the precursor solutionaccording to Examples I-1 to I-4 and Comparative Example 1 are evaluatedwith respect to hysteresis characteristics according to amounts ofmagnesium. Hysteresis characteristics are evaluated as follows: forwardbias and backward bias are applied to the thin film transistor andvoltage changes at a predetermined or given current between forward biasand backward bias application are measured.

The evaluation results are described referring to FIGS. 2A and 2B. FIGS.2A and 2B are graphs showing hysteresis characteristics of the thin filmtransistors according to Examples I-1 to I-4.

In more detail, FIG. 2A is a graph showing results of the thin filmtransistor according to Example I-2, and FIG. 2B is a graph showingresults of the thin film transistor according to Example I-3.

Hysteresis characteristics are deemed improved when voltage changes at‘A’ portion of the forward bias curved line (FB) and backward biascurved line (BB). As shown in FIG. 2A, at an ‘A’ portion, two curvedlines (FB, BB) are nearly overlapped indicating improved hysteresischaracteristics.

Likewise, in FIG. 2B, at an ‘A’ portion, two curved lines (FB, BB) arenearly overlapped indicating improved hysteresis characteristics.

Performance Evaluation 3

The thin film transistors fabricated using the precursor solutionsaccording to Examples II-1 to II-3 are evaluated with respect to chargemobility and turn-on voltage.

The evaluation results are shown in the following Table 2 and FIG. 3.

FIG. 3 is a graph showing the current characteristics of the thin filmtransistors according to Examples II-1 to II-3. In FIG. 3, ‘A’, ‘B’, and‘C’ are current characteristics of the thin film transistors accordingto Examples II-1 to II-3, respectively.

TABLE 2 Example II-1 Example II-2 Example II-3 Mg/Zn 0.1 0.3 0.5Mg/(In + Zn) 0.025 0.075 0.125 Mobility (at 10 V) 2.3 0.2 0.02 (cm²/Vs)Turn-on Voltage −17 −10 10 (V)

Referring to Table 2 and FIG. 3, the thin film transistor according toExamples II-1 to II-3 shows a lower threshold voltage and more stablecharge mobility of 0.5 cm²/Vs or more.

Performance Evaluation 4

The thin film transistors fabricated using the precursor solutionsaccording to Examples III-1 to III-3 are evaluated with respect tocharge mobility and turn-on voltage.

The evaluation results are shown in the following Table 3 and FIG. 4.FIG. 4 is a graph showing the current characteristics of the thin filmtransistors according to Examples III-1 to III-3.

TABLE 3 Example III-1 Example III-2 Example III-3 Mg/Zn 1 2 4 Mg/(In +Zn) 0.1 0.2 0.4 mobility(at 10 V) 0.7 2.7 0.4 (cm²/Vs) Turn-on Voltage−12.5 −3 −1 (V)

Referring to Table 3 and FIG. 4, the thin film transistors according toExamples III-1 to III-3 shows a lower turn-on voltage and more stablecharge mobility.

Performance Evaluation 5

The thin film transistors according to Examples IV-1 to IV-4 andComparative Example 2 are evaluated with respect to mobility, thresholdvoltage and current ratio.

The evaluation results are shown in the following Table 4 and FIG. 5.FIG. 5 is a graph showing the current characteristics of the thin filmtransistors according to Examples IV-1 to IV-4 and Comparative Example2.

TABLE 4 Max Minimum Current Current Threshold Current mobility(I_(d, max)) (I_(d, min)) Voltage(V_(th)) ratio(I_(on)/I_(off)) (cm²/Vs)Example HfIZO[Hf/Zn = 0.05] 6.01 × 10⁻⁵ 8.92 × 10⁻⁹  1.55 6.75 × 10³1.22 IV-1 Example HfIZO[Hf/Zn = 0.1] 5.26 × 10⁻⁵ 1.45 × 10⁻¹¹ 2.06 3.64× 10⁶ 1.25 IV-2 Example HfIZO[Hf/Zn = 0.2] 3.22 × 10⁻⁵ 9.93 × 10⁻¹² 3.493.24 × 10⁶ 0.81 IV-3 Example HfIZO[Hf/Zn = 0.3] 1.33 × 10⁻⁵ 6.30 × 10⁻¹²11.17 2.11 × 10⁶ 0.57 IV-4 Comparative IZO 3.00 × 10⁻⁴ 2.14 × 10⁻⁶ −24.05 1.41 × 10² 1.16 Example 2

Referring to Table 4 and FIG. 5, the thin film transistor according toExamples IV-1 to IV-4 shows a lower threshold voltage, a higher currentratio, and more stable charge mobility of 0.5 cm²/Vs or more. On thecontrary, the thin film transistor according to Comparative Example 2shows a higher threshold voltage and a lower current ratio due to higherminimum current (off current, I_(off)). Therefore, hafnium indium zincoxide (HfIZO) semiconductor thin film improves properties of the thinfilm transistor.

Performance Evaluation 6

The thin film transistors fabricated using the precursor solutionaccording to Examples IV-2, IV-3 and Comparative Example 2 are evaluatedwith respect to hysteresis characteristics.

The evaluation results are described referring to FIGS. 6A and 6B. FIGS.6A and 6B are graphs showing hysteresis characteristics of the thin filmtransistors according to Examples IV-2, IV-3 and Comparative Example 2.

In more detail, FIG. 6A is a graph showing results of the thin filmtransistor according to Example IV-2, and FIG. 6B is a graph showingresults of the thin film transistor according to Example IV-3

As shown in FIG. 6A, at the ‘A’ portion, two curved lines (FB, BB) arenearly overlapped indicating improved hysteresis characteristics.Likewise, in FIG. 6B; at the ‘A’ portion, two curved lines (FB, BB) arenearly overlapped indicating improved hysteresis characteristics.

The above description is given for a thin film transistor of a bottomgate structure, but is not limited thereto. The thin film of exampleembodiments may similarly apply to a thin film transistor of anystructure, e.g., a top gate structure. The above description is givenfor an oxide semiconductor applied to a thin film transistor, but is notlimited thereto. The oxide semiconductor of example embodiments maysimilarly apply to any electronic device requiring a semiconductor thinfilm.

While example embodiments have been described, it is to be understoodthat example embodiments are not limited to those disclosed herein, but,on the contrary, are intended to cover various modifications andequivalent arrangements included within the spirit and scope of theappended claims.

1. A solution composition for forming an oxide thin film, comprising: afirst compound including zinc; a second compound including indium; and athird compound including magnesium, wherein the zinc and magnesium isincluded at an atomic ratio of about 1:0.01 to about 1:4.
 2. Thesolution composition of claim 1, wherein the zinc and indium areincluded at an atomic ratio of about 1:10 to about 10:1.
 3. The solutioncomposition of claim 1, wherein the zinc and indium are included at anatomic ratio of about 1:5 to about 5:1.
 4. The solution composition ofclaim 1, wherein the zinc and indium are included at an atomic ratio ofabout 1:10 to about 1:1.
 5. The solution composition of claim 1, whereinthe zinc and indium are included at an atomic ratio of about 1:5 toabout 1:1.
 6. A solution composition for forming an oxide thin film,comprising: a first compound including zinc; a second compound includingindium; and a third compound including at least one of magnesiumacetate, magnesium alkoxide, magnesium halide, magnesium nitrate,magnesium sulfate, magnesium carbonylate, magnesium carbonate, andhydrates thereof.
 7. The solution composition of claim 6, wherein thefirst compound includes at least one of zinc hydroxide, zinc alkoxide,zinc citrate, zinc acetate, zinc carbonylate, zinc carbonate, zinc(meth)acrylate, zinc nitrate, zinc acetylacetonate, zinc halide, zincthiocarbamate, zinc sulfonate, zinc undecylate, zinc phosphate, zincborate, and hydrates thereof, and the second compound includes at leastone of indium hydroxide, indium alkoxide, indium citrate, indiumacetate, indium carbonate, indium (meth)acrylate, indium nitrate, indiumacetylacetonate, indium halide, indium thiocarbamate, indium sulfonate,indium undecylate, indium borate, and hydrates thereof.
 8. The solutioncomposition of claim 7, wherein the first compound includes zinc acetatehydrate and the second compound includes indium nitrate hydrate.
 9. Thesolution composition of claim 1, further comprising: at least one of analcohol amine compound, ketone compound, an acid compound, a basecompound, and deionized water.
 10. An electronic device comprising anoxide semiconductor including zinc, indium, and magnesium, wherein theoxide semiconductor includes the zinc and magnesium at an atomic ratioof about 1:0.01 to about 1:4.
 11. The electronic device of claim 10,wherein the zinc and indium are included at an atomic ratio of about1:10 to about 10:1.
 12. The electronic device of claim 10, wherein thezinc and indium are included at an atomic ratio of about 1:5 to about5:1.
 13. The electronic device of claim 10, wherein the zinc and indiumare included at an atomic ratio of about 1:10 to about 1:1.
 14. Theelectronic device of claim 10, wherein the zinc and indium are includedat an atomic ratio of about 1:5 to about 1:1.
 15. The electronic deviceof claim 10, wherein the electronic device is a thin film transistor,further comprising: a gate electrode overlapped with the oxidesemiconductor; a source electrode electrically connected to the oxidesemiconductor; and a drain electrode electrically connected to the oxidesemiconductor and facing the source electrode.